To determine the attitude of a satellite, it is known practice to install a stellar sensor in the satellite. Such a stellar sensor is an optical sensor which observes an area of space, and which determines the attitude of said satellite as a function of the positions of stars in its field of view. However, the measurements performed by a stellar sensor are sometimes too noisy to make it possible to determine the attitude of the satellite with sufficient accuracy, based only on the measurements of the stellar sensor.
It is also known practice to determine the attitude variations of an artificial satellite by installing gyrometers in the satellite. The gyrometers are kinetic sensors which measure the speed of rotation of the satellite, a speed of rotation which makes it possible to determine the attitude variations of the satellite. In practice, it is not uncommon to have four gyrometers or more in a satellite, to determine the attitude variations of said satellite.
The current attitude determining devices are generally provided with both gyrometers and a stellar sensor. Such devices make it possible to determine the attitude of the satellite with good accuracy, because the measurements supplied by the gyrometers make it possible to filter the measurement noises of the stellar sensors. However, such devices are costly, in particular because of the presence of numerous gyrometers.